Thanks for your response. I solved the issue by deleting the .altera.quartus directory which was created in the home directory after sourcing the setup and launching the tool. Now, I am able to launch the GUI. It was on Linux, 18.0 Quartus version, SC terminal/Konsole.
Thanks, good to hear that.
Deleting .altera.quartus means delete the setting that had make for Quartus. It is like make the Quartus to a default condition on the new computer.